Corner lock for corrugated fiberboard boxes



Patented Nov. 24, 195.3

UNITED orari-cie afcorporation Application May 12, 1951"', S'erial No; liii This` invention relates to. ai corner lockstr uc ture for corrugated fibre board. boxes ofthe-type wherein the corrugations of 4the-fibre board-.have some resiliency in bending. l

It is the object of the invention to provide a simple, convenient and positive-corner lock for securingv a corrugated brerboard box structure when. set' up from al blank. By. meansv of' the corner' lo'c'k'` as hereinafter more'v particularly' set forth and described, the side and end walls may be readily and conveniently interlocked merely by applying nger pressure to a bayonet type camming tongue extending from a flap in one of the walls to force it through Vand into camming engagement with a hinged locking flap provided in an opening of the adjacent wall, whereupon they become readily self locking in the setting up of the box from a blank.

The full nature of the invention will be understood from the accompanying drawings and the following description and claims:

Fig. 1 is a perspective View of a box with the lid removed showing the side and end walls interlocked.

Fig. 2 is an elevation of a section of the corner of the box before interlocking.

Fig. 3 is an enlarged portion illustrative of the locking tongue entering the receiving aperture.

Fig. 4 is a central vertical section taken on the line 4 4 of Fig. 3, illustrative of the camming action of the lock.

Fig. 5 is an enlarged view of the inside corner of the box with the locking tongue and ilap in interlocked relation.

In the drawings there is illustrated a box structure particularly shown herein as a chick box with the lid removed, and having side walls I0, end walls Il and a bottom I2. Said box is preferably formed of corrugated fibre board with the corrugations extending vertically in the end walls and horizontally in the side walls. Each of the side Walls terminates in a corner flap I3 curved upwardly and laterally from the lower corner of the box toward the upper edge.

Extending laterally from the corner nap and integral therewith there is a bayonet type tongue, with the corrugations thereof extending horizontally relative to the walls of the box, `as indicated generally at I4. Said tongue comprises a central nger portion I5 hinged to the corner flap I6. On each side of said linger portion and slightly scored at Il there are opposed camming and locking ears I8. Said ears are curved along their forward camming edge, having straight 2 rearward edgesi norrnally lying-1in' spaced rela'- ton to the forward edgeloftlie"A corner flap The'A endwalls'l II with the vertical' corrugat'iosl are eachI provided withy -alockreceiving opening I 9i' havingy a lockingl flap` 20; Said lock'-i ing flap` is,Av hinged to` the end'- wall Ill by' al scOri'ngf indicated at" 2-I and the-free end thereof is spaced? from'l the opjgiositeA edge! of' the'fopeni-ng! I9 sui'cient-ly to aocol'rinl'odate-thetongue I4 wlie'ri in locking position as shown in Fig. 2.

In operation, the flap I3 is set over in position for locking as shown in Fig. 3 whereupon the operator applies finger pressure inwardly against the central finger portion I5 of the tongue I4. By pushing in on sai-d linger portion the locking ears I8 are bent downwardly and outwardly as shown in Fig. 3 with the curved camming edge Ita in oamming engagement with the locking flap 25 as shown in Fig. 4. Such camming engagement between the ears and flap swings the flap inwardly until said ears disengage said flap whereupon it snaps back to its original position as shown in Fig. 5. Thereupon the locking ears which have been bent to a horizontal position in passing through the opening I9 resume their outstanding positions as shown in Figs. 2 and 5 to lie adjacent the inner surface of the end II of the box in locked engagement with the opening therein by reason of the tongue then extending through the relieved space of the opening I9.

It will be noted that the corrugations of the side wall I@ extend horizontally thereof and, therefore, longitudinally of the locking tongue I4 whereby the locking ears I 8 may readily flex thereon at I1 into camming position as shown in Fig. 4, and immediately resume their outward extending locking position upon being freed of their camming action, as shown in Fig. 5. On the other hand, the corrugations of the end walls extend vertically thereof so that the locking flap I5 has its corrugations extending transversely thereof and parallel to its hinged end 2I. This permits ready exing about the hinged end as it is cammed inwardly by the camming action of the ears I8, and upon disengagement will return to its normal position in the plane of the end wall and locking position.

The invention claimed is:

1. In a fibre board box structure formed from a blank to provide side and end walls, a corner lock for securing the adjacent ends of said walls in box formation, a tongue portion extending from the terminal edge of one of said walls having opposed laterally extending locking ears bendable thereon, each of said ears having its forward and lateral edge curved throughout its length to present a continuous camming face, and a locking flap cut from a tongue receiving locking opening in the said adjacent Wall with one end thereof hinged thereto at its far side from said tongue, said locking nap being tapered inwardly from its hinged end toward its free end and being wider at its hinged end than the tongue portion between the lines of bend of said ears to intercept and be engageable by the camming faces of said ears to be cammed inwardly thereby to substantially the length of said tongue for admitting said tongue through said opening and to permit said flap to thereupon return to normal position upon its disengagement by said tongue with the tongue extending on the opposite side thereof from its said Wall, whereby said ears Will be freed from canirningl engagement with said ap to extend into interlocking engagement with the adjacent Wall, substantially as shown and described.

2. Securing means for joining a pair of fibre board walls of a box structure, a tongue portion projecting from an edge of one of said Walls and having its outer end disposed in substantial parallelism with the said wall edge, locking ears projecting laterally from said tongue portion and bendable thereon and having their outer edges curved to form camming faces joining with said tongue end in substantial alignment with the sides of said tongue portion, the companion box Wall having an opening whose inner edge is of a Width substantially equal to the breadth of said tongue portion, a locking ap conforming to the Width of said opening projecting into the same from the outer edge thereof, and the end walls of said opening and flap diverging from the inner edge of said opening to the outer edge thereof to provide a surface engageablle by said locking ears whereby the edges of said divergent end Walls near` the outer ends thereof and the said iiap member will be engaged by the camming faces of said tongue when said tongue is forced into said opening.

KENNETH C. FERGUSON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,150,490 Bingaman Aug. 17, 1915 2,120,470 Patterson June 14, 1938 2,264,208 Inman Nov. 25, 1941 FOREIGN PATENTS Number Country Date 398,044 Great Britain Sept. 7, 1933 829,595 France June 30, 1938 

